Another part of the ichthyological survey was carried out in the Sokoľanský stream. This time, our ecologists, in cooperation with experts from the University of Prešov, found out how fish behave when we turn off the wastewater treatment plant, i.e. we literally turn off the stream and the flow in it stops. It is difficult for the life of fish especially in the summer months.
"The collection took place in mid-July. There are no official results yet, but when we compared it with the spring sampling, which we did during the normal operation of the WWTP and in colder weather, there were now much fewer fish. Life seems to have stopped there. The longer the shutdown, the worse the conditions for the fish, especially in the summer, when there is less water, which also has a lower oxygen content," said Miloš Fodor, GM for the environment.
University students who worked under the guidance of experienced experts also participated in the survey. They carried out similar research twenty years ago, which will allow a comparison of historical and current data.
Good conditions for white lowland fish
The values will never be the same as natural rivers and streams, because the Sokoľanský stream is basically our treated wastewater. Grayling or trout will never live in it, but it still provides good conditions for white lowland fish, which are not so demanding on water quality and oxygen content. Mainly shearwaters, barbels and crucian carp live here.
Ecological flow as an obligation
In the future, the Water Act envisages that every industrial company that uses water from a stream or river for its production purposes will have to ensure the so-called ecological flow. This means that it will be determined exactly how much water must remain in the stream or river in order to maintain optimal living conditions.
Miloš Fodor said: "It will also be more difficult because the climatic conditions will constantly deteriorate, there will be less water and it will be very difficult to maintain the set ecological flow. The limits of pollutants will be increasingly strict, which may also result in more frequent shutdowns of the wastewater treatment plant, which will have a more significant impact on life in the Sokoľanský stream."
The third survey will be in the autumn
They are planning a third survey in the autumn, under normal operating conditions, the data obtained and collected will be enough for comparison. The results of the polls will be known at the end of the year.
The main monitored toxic substances in the Sokolianský stream include phenols, ammonia and cyanides, but there are many more controlled parameters. Last year, we did not exceed the permitted limit of pollutants even once. In the case of wastewater, the limits can be exceeded seven times a year up to 1.2 times the limit for the pollutant.
